There’s several instruments that don’t require pinkies to play, but the harp is the only one that the priests teach.  Ishar can’t sing (can’t carry a tune, has trouble getting the words out properly, etc) and also doesn’t have the talons that a purebred skyborne would need for their instruments, so she ended up learning to play the harp.  She never owned a full-size one, but she does have a travel harp that she keeps on display (she also keeps it maintained and tuned, but no one’s ever heard her play it).